1. Field of the Invention
The present invention pertains to a heat exchanger primarily used for an automobile air conditioner.
2. Description of the Related Art
In the past, a heat exchanger, e.g. the one disclosed in Japanese Kokai Patent Utility Model Publication No. 63-154985, included, as shown in FIG. 17 and FIG. 18, a tubular element 1b having an inlet/outlet unit 3 comprising a barrel-shaped element 17 formed of integral parts of two molded plates of the tubular element 1b. The inlet/outlet unit 3 protrudes from a tank 18 of the tubular element 1b. The tubular element 1b is formed by soldering the two molded plates together along a seam 16 running therebetween after a spacer 6 has been inserted in an insertion hole 25 of the inlet/outlet unit 3.
In the method of attaching an inlet/outlet pipe 5 to the spacer 6, in the aforementioned prior art, the inlet/outlet pipe 5 is inserted into the spacer 6 and secured to it by means of argon soldering or torch blazing.
In the aforementioned prior art, however, there is a problem that the joint of the inlet/outlet unit 3 was expanded outwardly when the spacer 6 was pushed into the inlet/outlet unit 3, causing a large gap between the joint unit and spacer 6, whereby the soldering resulted in a defect in the joint between said inlet/outlet unit 3 and spacer 6, allowing the heat-exchanging medium to leak.
There has been a demand that the spacer be eliminated to reduce the cost for a heat exchanger. However, if the inlet/outlet pipe 5 is directly secured to inlet/outlet unit 3 due to the absence of spacer 6, torch blazing must be used. In this case, however, a problem arises in that since the plates at the inlet/outlet unit 3 are as thin as approximately 0.6 mm, the inlet/outlet unit 3 would be melted if directly contacted by a flame during torch blazing, thereby damaging the inlet/outlet unit 3 and creating a defective sealing of the inlet/outlet unit. There also is an apprehension that the inlet/outlet unit will lack rigidity and that the positioning of the inlet/outlet pipe will become difficult.
In addition, Japanese Kokai Patent Utility Model Publication No. H4-129691, which was filed by the same applicant who has filed the application of the present invention, predating the application of the present invention, discloses a structure wherein the soldering seam terminates prior to the end of the inlet/outlet unit, a ring is placed on the inlet/outlet unit at the end thereof, and a spacer is attached to the inlet/outlet unit. The inlet/outlet pipe is secured to the heat exchanger by means of this spacer.